1. Field of the Invention
The invention is generally related to the correction of certain signal impairments in a wireless communication system. More specifically, the invention is directed to the estimation and correction of carrier frequency offset, sampling frequency offset, and phase noise in a wireless communication system.
2. Background
A wireless communication system will typically employ at least one transmitter/receiver pair between which data carrying signals are exchanged. In such a wireless system, the transmitter is typically responsible for encoding the digital information and modulating it onto an analog carrier signal (e.g., a radio signal). Subsequently, the receiver demodulates and decodes the digital information. There are many known techniques for the modulation and demodulation of digital information sent via analog carrier signals.
Regardless of the specific modulation technique used in a given wireless system, the analog carrier signal is subject to certain impairments or degradations during the modulation-transmission-demodulation cycle. Such impairments manifest themselves in a variety of ways including carrier frequency offset (CFO) and sampling frequency offset (SFO). Phase noise is an additional impairment. These impairments, if left uncorrected, can result in corruption of the digital information.
As modulation techniques grow ever more sophisticated, the complexity, speed and sensitivity of wireless communication systems are constantly pushed to the limit. It would be beneficial, then, to continually seek improvements in the estimation and correction of CFO, SFO, phase noise and other such impairments to wireless communication signals.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the leftmost digit or digits of a reference number identify the figure in which the reference number first appears.